The Associated Press reports that the North Korean army is warning Washington that its military has been cleared to wage an attack using "smaller, lighter and diversified nuclear" weapons.

The threat from the unnamed army spokesman early Thursday is latest in a series of escalating warnings from North Korea, which has railed for weeks against joint U.S. and South Korean military exercises taking place in South Korea and has expressed anger over tightened sanctions for a February nuclear test.

SEE PHOTOS - Revealing images from inside North Korea below

The spokesman said in a statement carried by the Korean Central News Agency that troops have been authorized to counter U.S. aggression with "powerful practical military counteractions." The Pentagon said Wednesday it will deploy a missile defense system to Guam to strengthen the region's protections against a possible attack.

Pyongyang is believed to be working toward building an atomic bomb small enough to mount on a long-range missile. Earlier this week North Korea vowed to restart operations at the country’s only nuclear reactor. The plutonium plant was shuttered in 2007 as part of an international disarmament deal.

The BBC published the strike authorization statement carried by the official North Korean news agency:

"We formally inform the White House and Pentagon that the ever-escalating US hostile policy towards the DPRK [North Korea] and its reckless nuclear threat will be smashed by the strong will of all the united service personnel and people and cutting-edge smaller, lighter and diversified nuclear strike means of the DPRK and that the merciless operation of its revolutionary armed forces in this regard has been finally examined and ratified."

Los Angeles tops the list of U.S. metropolitan areas with the highest Korean American populations, according to 2010 Census data. Additionally, over 3,300 students of Korean heritage study at UCLA, the most of any university in the United States, according to the school'sCenter for Korean Studies.

PHOTOS

Associated Press chief photographer for Asia David Guttenfelderhas been sharing via Instagram his iPhone photos from Pyongyang. According to Guttenfelder's account bio, he is on assignment for National Geographic Magazine.